This invention relates to engine cylinder deactivation apparatus and, in particular, to apparatus having switching valve actuators controlled by rotary valve sleeves.
It is known in the art of engine cylinder deactivation to provide switchable hydraulic valve actuators operable to either actuate the valves of a deactivation cylinder or to maintain the valves closed through lost motion features of the valve actuators. The valve actuators may be either stationary hydraulic lash adjusters or hydraulic valve lifters, both of which may include internal hydraulic lash adjusting mechanisms and so may be referred to broadly as a hydraulic lash adjusters or valve actuators.
Conventional valve actuators having lash adjusters are supplied with pressurized oil through a lash adjuster gallery or lifter gallery to annular feed grooves or intake ports. The pressurized oil operates with the lash adjusting mechanisms to take up lash in the valve train between the valve and its associated tappet or other actuator. Valve actuators with cylinder deactivation may have an additional port for a lock pin which connects through control passages and a control channel with a valved oil pressure supply. A three-way solenoid-actuated hydraulic control valve may be used to connect oil pressure to unlatch the lock pin for cylinder deactivation or switching of the valve actuators in a supply mode of the three-way valve, and to exhaust oil pressure from the oil passages and control gallery in an exhaust mode to return to normal engine valve operation.
Such cylinder deactivation apparatus typically use complex systems of bypass channels and hydraulic bleeds in order to purge air or other gas/vapor from the system to insure consistent response to control signals. This is necessary to provide reliable actuation or deactivation of the switchable hydraulic valve actuators in the apparatus when the hydraulic control valve is actuated to make a change in operation. These bleed and bypass systems may add considerable complexity to the deactivation apparatus itself. Thus, a simplified system for purging gas/vapor, primarily air, from the hydraulic cylinder deactivation apparatus is desired.
The present invention provides cylinder deactivation apparatus having a simplified hydraulic circuit featuring a single oil supply which supplies oil to both conventional and deactivation valve actuators for lubrication of associated valve mechanism and the operation of internal lash adjusters. The single oil supply further provides oil to cylinder deactivation mechanisms in the switching valve actuators. Rotary valve sleeves are provided surrounding each of the switching valve actuators. The sleeves act to admit continuous pressurized oil to the internal lash adjuster mechanisms and to selectively control the flow of oil from the lash adjuster mechanism inlets to the deactivator switching mechanisms, as well as to control the discharge of pressure oil from the deactivator switching mechanisms.
When a rotary sleeve is positioned in a first valve actuating position, an exhaust port in the rotary sleeve is aligned to drain oil from the deactivating mechanism while pressure oil to the mechanism is cut off so that the associated engine valves are operated normally. Rotation of the rotary sleeves to a second deactivation position closes the exhaust port flow and opens a transfer port from the lash adjuster oil feed to the deactivation mechanism to supply it with full pressure oil. This operates the deactivation mechanism, switching the lifter to the deactivated mode, which cuts off actuation of the valves by the switching valve actuators by unlatching their latch pins or lock pins and allowing the deactivation mechanism to telescope inside the valve actuator. In this way, control of the valve actuators and the actuating oil flow is concentrated at the rotary valve sleeves and the connecting hydraulic supply and exhaust passages adjacent to the valve actuators. A simplified internal passage system is thus provided with activation by rotary valves at each of the switching actuators. Simple linkages or actuating arms may be provided for rotating the rotary sleeves and may include separate drivers for each of the switchable engine cylinders.
These and other features and advantages of the invention will be more fully understood from the following description of certain specific embodiments of the invention taken together with the accompanying drawings.